Na+/K+ATPase in Lower Airway Epithelium from Cystic Fibrosis and Non-Cystic-Fibrosis Lung

Abstract

The basolateral Na+/K+ATPase plays a critical role in sodium reabsorption across airway epithelium. Nasal epithelium shows increased Na+/K+ATPase activity in cystic fibrosis (CF) but Na+/K+ATPase has not been characterized in human lung epithelium or compared in CF and normal lung. We measured3[H] ouabain binding and Na+/K+ATPase activity in human tracheal epithelium and compared Na/K ATPase activity in bronchial epithelium in CF and control subjects. In tracheal epithelium Na+/K+ATPase pumps were abundant and of high3[H] ouabain affinity (Kd 4.7 nM, Bmax38 pmol/mg) and Na+/K+ATPase activity was 55±8 nmol/mg protein/min. Bronchial epithelial Na+/K+ATPase activity was twofold higher in CF patients than in controls. The increased Na+/K+ATPase activity may contribute to the increased sodium reabsorption seen in cystic fibrosis.